A scanning electron microscopy (SEM), a typical charged particle beam device, irradiates the surface of the specimen to be examined with electron beam (primary electron beam) by scanning it two-dimensionally, and makes the intensity of quadratic electrons generated secondarily from the specimen as an input for brightness modulation to an image that is scanned and generated in synchronization with the scanning of the primary electron beam, to obtain an SEM image of the surface of the specimen. At this time, the surface of the specimen for examination is selected by moving the stage that is mounted with the specimen. Normally, the operator operates the operation input unit such as a trackball while observing an SEM image for moving the stage until the portion of the surface of the specimen is obtained as the SEM image. An SEM is used for examination of flaws and defects in a semiconductor pattern, or the like, and recently the SEM is required to have higher magnification for examination as a semiconductor process becomes more microscopic. Therefore, a stage used in the SEM is also required to move in a more microscopic way with higher accuracy.
Incidentally, when examining a specimen having a similar fine pattern (cell) continuously such as a semiconductor wafer, an examination position is determined by scanning the specimen at a constant speed in a predetermined direction and counting, visually or by image processing, the number of cells that passes through the SEM screen. This is called a cell count and in order to do this, a rotational movement (rotation) is required to align the direction of a translational movement of the stage with the scanning direction of the specimen. In addition, when the shape of the specimen is three-dimensional, it is desired for the specimen to be examined in three dimensions by changing the viewing direction, and this also requires rotational movement.
As the stage operation is performed while observing the SEM image, it is desirable for the specimen to be rotatable about a virtual point that is set in the SEM image so that the field of view does not move when rotating the specimen. This operational feature is called rotation eucentric feature. On a conventional stage, a positional variation of the rotation center in the SEM image has been large due to eccentricity and/or whirling of the rotation axis, or due to a looseness and/or a backlash in an actuator and/or a transmission mechanism, then it has been difficult to keep the rotation center in the SEM image, especially during examination with high magnification. Therefore, when rotating the specimen, it has been necessary to follow steps such as to perform rotation after lowering the magnification for examination, then to increase the magnification again while adjusting the position in translation movement, thus making the operation complicated. In addition, it has been difficult to perform the examination continuously while rotating the specimen. A technique for correcting such a positional variation of the rotation center is, for example, disclosed in Japanese Patent No. 4515179B.
In addition, in Japanese Patent Application Publication No. 2000-260379A, a technique is disclosed for a scanning electron microscope, for correcting the electron beam scanning area using reference marks provided outside of a stage. Additionally, Japanese Patent Application Publication No. 2007-018944A, a configuration is disclosed for forming marks on a specimen stage in a charged particle beam device. Further, in Japanese Patent Application Publication No. 2008-146990A, a configuration is disclosed for providing markings on a specimen fixing table in a charged particle beam device, to detect a positional error by an external imaging device.